1. Field of the Invention
This invention relates generally to infrared thermometers, and more particularly to a disposable insertion probe for use with a medical infrared thermometer.
2. Prior Art
Medical thermometers are useful in the diagnosis and treatment of many diseases. Measurement of a patient's body temperature has been most commonly performed by conventional mercury thermometers. Disadvantages of such thermometers are that accurate readings often require a minute or more, and such thermometers need to be sterilized before each use. Electronic thermometers have become popular because they require far less time for an accurate reading of a patients temperature, and the probe of the electronic thermometer is commonly inserted into a protective disposable cover before use. Such electronic thermometers are rapidly reusable and are generally sanitary when used with sanitary sheaths. However, an accurate reading of a patient's temperature still may require as much as 30 seconds, since the temperature is measured through the sanitary sheath which must equilibrate to the patient's temperature. Such thermometers are also generally used orally or rectally.
The auditory canal and the tympanic membrane are also useful for measurement of a patient's internal body temperature. An electronic thermometer utilizing a thermocouple for measuring the temperature of the tympanic membrane by directly contacting the tympanic membrane is described, for example, in U.S. Pat. No. 3,531,992. However, such devices have the disadvantage of causing discomfort to the patient, and the probe is either inserted without a sheath, thus requiring sterilization between uses, or else utilization of a sheath or speculum generally prolongs the time in which temperature is measured.
Infrared thermometers avoid the necessity of contacting the location at which temperature is actually being measured, and have also been designed for use in measuring the patient's temperature from the auditory canal or from the tympanic membrane. One such device is described in U.S. Pat. No. 3,282,106 (Barnes). An infrared detector receives infrared radiation from the auditory canal through an internally polished truncated cone which serves as a shield and an insulator, so that temperature readings are only taken from the auditory canal. A similar infrared thermometer for measuring body temperature through the auditory canal is described in U.S. Pat. No. 3,878,836, (Twentier) which focuses the insertion probe of the device toward the tympanic membrane. A disposable speculum is also placed completely over the insertion probe for sanitary purposes. However, the speculum and probe are open at the forward end, allowing contamination of the probe by earwax or other debris, so that the insertion probe actually requires cleaning sterilization to be assured of sterile and effective use. A disposable speculum for an infrared thermometer insertion probe is also described in U.S. Pat. No. 4,662,360 (O'Hara et al.), but this disposable speculum also includes a film of protective plastic material at the forward end of the speculum to prevent contamination and clogging of the insertion probe. The film covering the disposable speculum is substantially transparent to infrared radiation. The body portion of the speculum fits onto the insertion probe so that the membrane is stretched tightly over the tip of the insertion probe, to remove any wrinkles in the membrane. An infrared thermometer with which the disposable speculum may be used is also shown in U.S. Pat. No. 4,602,642 (O'Hara et al.) There remains the disadvantage with this type of thermometer that a certain amount of infrared radiation is still absorbed by the film over the speculum, and the pressure of the insertion probe against the membrane allows for the possibility of breakage of the protective membrane during a temperature measurement due to stresses placed on the speculum and insertion probe, and possibly due to manufacturing defects in the membrane itself, or in the attachment of the membrane to the speculum. Other problems in achieving an accurate temperature reading can be caused by the film membrane, so that it would be desirable to have the forward end of the insertion probe not covered by a protective membrane. It is at the same time desirable to avoid contamination of the insertion probe, which may lead to the spread of infection from patient to patient or which would otherwise require cleaning and sterilization between uses. An infrared thermometer with such an insertion probe could be rapidly reused, and could provide accurate readings, in a matter of a few seconds, or less.